Whey-contaiing food product and method of deflavoring whey protein

ABSTRACT

Whey protein materials such as whey from cheese making processes, whey protein concentrates, and whey protein isolates, are deflavored by adjusting the pH of an aqueous composition of such whey protein materials to about 8 to about 12 to solubilize the whey proteins and to release the flavoring compounds and thereafter passing the pH-adjusted composition to an ultrafiltration membrane having a molecular weight cutoff up to about 50,000 Daltons under conditions at which the flavoring compounds pass through the membrane, leaving the retained whey protein material with improved flavor.

The present application is a continuation-in-part application of U.S.patent application Ser. No. 09/939,500, filed Aug. 23, 2001, which wasbased on, and claimed benefit of, U.S. Provisional Application Ser. No.60/250,228, filed on Nov. 30, 2000, both of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates generally to the processing of wheyprotein-containing materials for use in various food products. Moreparticularly, the invention relates to a method of deflavoring wheyprotein materials in order to make them acceptable in a wide range offoods.

In recent years, whey proteins have become widely used in food products,for the health benefits to be obtained from their use. For example,studies suggest that whey proteins may provide a variety of healthbenefits such as anti-hypertension activity, immune system enhancement,antimicrobial activity, intestinal health enhancement, and oral hygieneactivity. In some applications, the taste of the whey protein materialsis not objectionable. However, in some uses, such as dairy analogproducts, beverages and the like, and especially when the amount of wheyprotein is increased to the levels associated with such health benefits,the flavors found in whey protein materials may prevent their readyacceptance by the consumer. Thus, in order to extend the uses of wheyprotein materials, the present inventors wanted to find a method ofreducing the flavor components of whey protein materials. However, itwas not evident that methods which had been used previously to removeflavor components from other organic materials would be successful inthe treating of whey protein materials. Organic materials, since theyhave complex compositions, must be tested to determine whether any givenmethod of treating them will be satisfactory.

One example of previously employed methods to purify organic materialsis found in U.S. Pat. No. 4,477,480, in which the patentees show thatstarch can be treated with an alkali to remove objectionable flavorcomponents. In a commonly assigned patent, U.S. Pat. No. 4,761,186,ultrafiltration is used to purify starch. In both cases, flavorcomponents are removed from the starch, in the '480 patent bysolubilizing the flavor components so that they can be washed out of therelatively insoluble starch. In the '186 patent, ultrafiltration wasused to remove the flavor components as permeate, while the insolublestarch remained in an aqueous slurry. By contrast, the present inventionseparates flavor components from soluble high molecular weight wheyproteins.

There are many articles and patents which relate to processing soymaterials in order to recover the protein content and which at the sametime reduce the flavor compounds to make the proteins more acceptable infood products. However, these previous disclosures were not specificallydirected to removal of flavoring compounds and recovering as much of theprotein as possible. One example is U.S. Pat. No. 4,420,425 in whichprotein components of soy are solubilized at a pH of 7 to 11, preferablyabout 8 and, after ultrafiltration through a membrane having a molecularweight cut off above 70,000, are recovered by spray drying the retainedsoy proteins. In variants, only a portion of the protein is solubilizedat lower pH values and subjected to ultrafiltration with a membranehaving a cutoff preferably above 100,000 molecular weight, the productwas found to have improved color and flavor. A higher cutoff valve wouldbe expected to result in a loss of valuable proteins. In another patent,U.S. Pat. No. 5,658,714, a soy flour slurry is pH-adjusted to the rangeof 7 to 10 to solubilize proteins, which are then passed through anultrafiltration membrane and phytate and aluminum are retained,presumably as solids. While the molecular weight cutoff of the membranewas not given, it is assumed that the pore size was large in order to beable to pass the soluble proteins. Both of these patents containextensive discussions of the efforts of others in the processing of soymaterials; neither teaches or suggests the control of pH during theultrafiltration process.

In a group of related patents, Mead Johnson Company disclosed processesfor solubilizing soy proteins by raising the pH of an aqueous solutionof soy materials and recovering the proteins which are said to have abland taste. The processes are principally directed to concentratingproteins rather than removing flavor compounds. In U.S. Pat. No.3,995,071, the pH was increased to 10.1 to 14 (preferably 11 to 12) tosolubilize soy proteins, after which the pH was lowered to about 6 to 10and ultrafiltration with a membrane having a molecular weight cutoff of10,000 to 50,000 Daltons was used to retain the proteins whilediscarding carbohydrates and minerals. In U.S. Pat. No. 4,072,670,emphasis was placed on removing phytates and phytic acid by solubilizingproteins at a pH of 10.6 to 14 and a temperature of 10 to 50° C. to makethe phytates and phytic acid insoluble, then separating them and finallyacidifying the solution to a pH of about 4 to 5 to precipitate the soyproteins. In U.S. Pat. No. 4,091,120 soy proteins were solubilized at apH less than 10, preferably 7 to 9, and ultrafiltration was used toseparate the proteins as retentate, while passing carbohydrates aspermeate. These patents do not teach or suggest control of the pH duringthe ultrafiltration process.

The present inventors wanted to remove compounds in soy proteinmaterials which contribute color and flavor and which interfere with theuse of soy protein in certain food products such as beverages, dairyanalogs, and the like. They found that soy protein-derived materials canbe treated successfully, recovering substantially all of the proteinsand rejecting the compounds which cause undesirable color and flavor.Moreover, by controlling the pH within the range of about 8.5 to about12 during the ultrafiltration process, deflavored soy protein materialshaving improved functional properties can be obtained. Thus, the productis suitable for many food products. Now the present inventors havesurprisingly discovered that a related process can be advantageouslyapplied to whey protein materials to remove undesirable flavorcomponents to obtain a deflavored whey protein material which can beincorporated into many different food products. The process can,however, be modified such that it can be operated in a basic or acid pHrange. Thus, either basic or acidic deflavored soy protein can beprepared using the process of this invention.

SUMMARY OF THE INVENTION

Broadly, the invention is a process for preparing an aqueous wheycomposition having a whey protein concentration of about 1 to about 50percent, which is pH-adjusted to solubilize the whey protein content andto release the flavoring compounds. Then the composition is subjected toultrafiltration, while maintaining pH control, using a membrane capableof retaining substantially all of the protein content of the wheyprotein material while removing flavoring components as permeate. Asnoted above, the present inventors have now surprisingly discovered thata method used for deflavoring soy protein materials can be used in asimilar manner for deflavoring whey protein materials. The presentprocess, as applied to whey proteins, can be run under either acidic orbasic conditions as desired to produce either an acidic or a basicdeflavored whey protein material.

The deflavored whey protein materials prepared by the present methodsare ideally suited for use in dairy and non-dairy beverages, smoothies,health drinks, confectionary type products, nutritional bars, cheeses,cheese analogs, dairy and non-dairy yogurts, meat and meat analogproducts, cereals, baked products, snacks, and the like. Preferably theacidic deflavored whey protein is used in acidic food products and thebasic deflavored whey protein is used in neutral and basic foodproducts. Thus, by proper selection, one can avoid destabilizing thedeflavored whey protein associated with passing it through itsisoelectric point.

The present invention provides methods for deflavoring whey proteins. Inaddition to the removal of off-flavors, the present invention alsoallows the efficient removal of lactose, thereby allowing concentrationof the whey proteins to high levels. Typically whey protein containsabout 70 to about 80 percent (dry basis) lactose. Generally, levels oflactose less than about 15 percent (dry basis) can be obtained in thedeflavored whey protein. By extensive ultrafiltration/difiltration(i.e., greater than 5 wash cycles and typically in the range of about 6to 7 wash cycles), the level of lactose can be reduce to less than about99 percent (dry basis). Moreover, the deflavored whey protein materialscan be prepared containing greater than about 50 percent protein (on adry basis), and preferably about 65 to about 95 percent protein;obtaining higher levels of protein (generally greater than about 85percent) require extensive ultrafiltration/diafiltration. Thus, itbecomes possible to incorporate whey protein in conventional foodproducts at sufficiently high levels (generally sufficient to provideabout 2.5 to about 20 g whey protein per single serving size (generallyabout 25 to about 100 g for solid food products and about 100 to about300 ml for liquid food products)) to provide health benefits of wheyprotein. Prior to this invention, incorporation whey proteins at suchlevels generally resulted in significant off-flavors and, therefore,only very limited acceptance by consumers. Moreover, the removal oflactose may allow the use of such food products by lactose-intolerantconsumers; generally, in such cases, at least about 95 percent of thelactose should be removed.

In one aspect, the invention is a method of deflavoring whey proteinmaterials, which method includes preparing an aqueous composition of thewhey protein material containing flavoring compounds, adjusting the pHto a basic range of about 8.5 to about 12 or to an acidic range of about2.4 to about 4 to solubilize the protein content of the whey proteinmaterial and release the flavor components, and then passing thepH-adjusted composition adjacent to an ultrafiltration membrane havingpores which provide a molecular weight cutoff up to 50,000 Daltons,while maintaining the pH in the same range as to which the aqueouscomposition was adjusted, thus retaining substantially all of the wheyprotein content, while passing through the pores the flavor producingcompounds.

In another aspect (herein termed the “basic mode of operation”), theinvention includes adjusting the pH to the range of about 8.5 to about12 with an alkali such as sodium, potassium or calcium hydroxides tomaintain the solubility of the whey protein content and release theflavor compounds, making it possible to separate such compounds byultrafiltration. Importantly, the pH in this basic mode of operation isalso controlled within the range of about 8 to about 12 during theultrafiltration process.

In another aspect (herein termed the “acidic mode of operation”), theinvention includes adjusting the pH to the range of about 2.5 to about 4with an edible acid (e.g., citric acid, acetic acid, lactic acid, malicacid, ascorbic acid, fumaric acid, adpidic acid, phosphoric acid, sodiumhydrogen sulfate, and the like) to maintain the solubility of the wheyprotein content and release the flavor compounds, making it possible toseparate such compounds by ultrafiltration. The preferred edible acidsfor use in this acidic mode of operation include phosphoric acid, citricacid, and malic acid. Importantly, the pH in this acidic mode ofoperation is also controlled within the range of about 2.5 to about 4during the ultrafiltration process.

Native whey proteins (i.e., undenatured) are generally soluble over awide range of pH values. Denaturing of such protein, as often occursduring processing (e.g., cheese manufacture, pasteurization, elevatedtemperature, ultrafiltration, and the like) have decrease solubility(especially around the isoelectric point of about 7.4). Maintaining thepH of the deflavored whey protein in essentially the same range as itsultimate use in a food product allows the maintenance of desiredsolubility. Using a deflavored whey protein prepared using the basicmode of operation in a neutral or basic food product and using adeflavored whey protein prepared using the acidic mode of operation inan acidic food products avoids modifying the pH of the deflavored wheyprotein (and passing it through its isoelectric point) and therebyprovides maximum solubility in the food product.

In one embodiment, the invention is a method for deflavoring wheyprotein materials in a continuous process wherein a pH-adjusted aqueousmixture of whey protein materials is passed adjacent an ultrafiltrationmembrane to separate the flavor components. The pH is maintained atabout 8.5 to about 12 for the basic mode of operation or at about 2.5 toabout 4 for the acidic mode of operation during the ultrafiltration bythe addition of the appropriate amount of an appropriate pH-alteringmaterial (i.e., a base or acid depending on the desired mode ofoperation). The permeate containing flavor components, lactose,minerals, and water is passed adjacent a reverse osmosis membrane todewater the permeate and the separated water is recycled to joinrecycled retentate and fresh pH-adjusted whey materials. A portion ofthe retentate is continually removed and the deflavored whey proteinmaterials recovered.

In a preferred embodiment, the invention is a method for deflavoringwhey protein materials in a batch or semi-continuous process wherein apH-adjusted aqueous mixture of whey protein materials is passed adjacentan ultrafiltration membrane, the permeate is separated for recovery ofthe flavor components, and the retentate is recycled to join freshpH-adjusted whey protein materials. Water is added periodically orcontinuously to replace the water lost to the permeate and to adjust theconcentration of whey materials in the combined stream to apredetermined level. If necessary, a pH-altering material (e.g., a baseor an acid) can be added to the recycled retentate or added water tocontrol the pH to the desired range during the ultrafiltration process.The process is continued until essentially all of the flavoringcompounds have been removed. If desired, the process can also becontinued until sufficient levels of lactose removal have been obtained;such reduced lactose materials may be used in food products directed tolactose-intolerant individuals.

In another preferred embodiment, the present invention provides a methodfor preparing deflavored whey protein material, said method comprising:

(a) preparing an aqueous composition of a whey protein materialcontaining soluble whey proteins and flavoring compounds;

(b) adjusting the aqueous composition of (a) to either (1) a basic pH inthe range of about 8.5 to about 12 or (2) an acidic pH in the rang ofabout 2.5 to about 4;

(c) passing the aqueous composition of (b) adjacent an ultrafiltrationmembrane having a molecular weight cutoff up to about 50,000 Daltons,while maintaining the pH in the same range as adjusted in step (b),under suitable ultrafiltration conditions wherein the flavor compoundspass through the membrane, thereby deflavoring the whey protein materialand retaining substantially all of the soluble whey proteins; and

(d) recovering the soluble whey proteins retained by the ultrafiltrationmembrane to obtain the deflavored whey protein material. It is generallypreferred that any insoluble materials be removed from the whey proteincomposition prior to the ultrafiltration step. Removal of such insolublematerials (which could include, for example cheese fines, fat globules,and casein aggregates using whey derived from a cheese making process)could be carried out at any time before ultrafiltration step, includingbefore the preparing the initial aqueous solution of step (a).

The ultrafiltration membrane used in the method of the invention willhave a molecular weight cutoff up to 50,000 Daltons, preferably 1,000 to50,000, most preferably about 10,000.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a block diagram of one process employing the invention.

FIG. 2 is a block diagram of a preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Whey Protein Materials. Whey proteins have high nutritive value forhumans. In fact, the amino acid composition of such whey proteins isclose to an ideal composition profile for human nutrition.Unfortunately, use of such whey proteins in food compositions have beenlimited due to undesirable odors and/or flavors as well as otherorganoleptic problems associated with whey proteins. Normal whey proteinmaterials generally have significant lactose, milky, and animal flavorswhich can impact the flavor profiles of food products, especiallyotherwise bland food products. Off flavors in whey protein materials aregenerally attributed to lipid oxidation of unsaturated fatty acidsduring, or after, the cheese making process and/or to Maillard browningreactions. Lipid oxidation can result in formation of volatilealdehydes, ketones, esters, and alcohols, which appear to contribute toa cardboard-like flavor. Typically, whey protein materials contribute,or provide, off flavors described as carboardy, musty, metallic, sour,cooked, astringent, and diacetyl; see, for example, Laye et al.,Milchwissenschaft, 50, 268-272 (1995); Carunchia Whetstine et al., J.Dairy Sci., 86, 439-448 (2003).

The present inventors have found that defects normally associated withwhey proteins can be significantly reduced, and in some caseseliminated, using the process of this invention. Deflavored whey proteinas produced by the present invention can not only be used in a widevariety of food products, but they can be used in higher levels that hasbeen possible before, thereby providing nutritionally superior foodproducts. Deflavored whey proteins can be prepared from, for example,whey obtained from conventional cheese making processes, whey proteinisolate, whey protein concentrate, and the like.

Ultrafiltration Membranes. Filtration is used to separate manymaterials. In the present invention, ultrafiltration is used to removeflavoring compounds from whey protein materials. Importantly, the pH ofthe whey protein material should be maintained in the range of about 8to about 12 during the ultrafiltration process. Ultrafiltration isintended to remove particles having a size between 10 to 1,000 Angstroms(0.001 to 0.1 μm), corresponding generally to particles having amolecular weight between 10,000 and 1,000,000, and which may also beaffected by the shape of such high molecular weight particles. Wheyproteins have molecular range between about 14,000 and 100,000. Atypical analysis of whey proteins is provided in the table below:Percentage of Total Whey Protein Faction MW (daltons) Whey ProteinsBeta-lactoglobulins 18300 50 Alpha-lactoalbumin 14000 12 Immunoglobulins15000-100,000 10 Bovine Serum Albumin 69000 5 Proteose-peptones4100-41,000 23A membrane may be chosen which is capable of passing all of the wheyproteins or only a selected portion. In the present invention, the wheyproteins are retained by the ultrafiltration membrane under the selectedoperating conditions, while the lower molecular weight flavoringcompounds pass through the membrane and are separated, thus improvingthe color and flavor of the retained whey proteins and associatedsolids.

A polymer ultrafiltration membrane may be defined as an anisotropic(non-uniform) layer. One face is a skin containing pores which determinethe size of molecules which can pass through the membrane. Supportingthe surface skin is a spongy structure which extends to the oppositeface. Such membranes are commonly made by coagulation of polymers in anaqueous bath. Typical polymers which are used include polysulfones,cellulose esters, poly(vinyldenefluoride), poly(dimethylphenyleneoxide), poly(acrylonitrile), which can be cast into membranes. Often,the membranes are formed into hollow tubes which are assembled intobundles, through which the solution to be filtered is passed.Alternatively, flat membrane sheets and spiral designs may be used. Incommercial practice, pressure is applied to facilitate movement of thelower molecular weight compounds through the membrane. The membrane mustbe able to withstand the pressures used, making it important that thespongy supporting structure be uniform to avoid breaking the surfaceskin and bypassing the membrane.

In addition to the polymeric membranes just described, other materialshave been used to make ultrafiltration membranes, such as ceramics,sintered metals, and other inorganic materials. The present invention isnot limited to any particular type of membrane. In general, the membranemust be able to pass the flavoring compounds, which are believed to havemolecular weights lower than 1,000 Dalton. More importantly, themembranes must be able to retain substantially all of the solubilizedwhey proteins. Thus, the membrane of the invention will have a molecularweight cutoff up to about 50,000 Daltons, preferably about 1,000 to50,000 Daltons, more preferably 10,000 to 30,000 Daltons.

Process. The process of the invention includes the following steps:

(1) Prepare an aqueous mixture of the whey protein material. In caseswhere the original whey protein material is an aqueous solution (e.g.,whey from a cheese manufacturing process), the material may be used asis, or additional water may be added or removed as desired, to form theaqueous mixture. For dried whey materials (e.g., whey protein isolate,whey protein concentrate, and the like), water will, of course, need tobe added to form the aqueous mixture.

(2) Determine whether to employ the basic or acid mode of operation.This determination will normally depend on the anticipated end use ofthe deflavored whey protein. If the deflavored whey protein is intendedto be used in a food product normally having a neutral or basic pH, thebasic mode of operation will be preferred. If the deflavored wheyprotein is intended to be used in a food product normally having anacidic pH, the acidic mode of operation will be preferred. For the basicmode of operation, add a base to raise the pH of the aqueous mixture toabout 8.5 to about 12 in order to maintain the solubility of the wheyproteins and to release the flavoring compounds. For the acidic mode ofoperation, add an acid to lower the pH of the aqueous mixture to about2.5 to about 4 in order to maintain the solubility of the whey proteinsand to release the flavoring compounds.

(3) Pass the pH-adjusted mixture, while maintaining the pH in the samerange as used in step (2) above, adjacent to an ultrafiltration membranehaving a molecular weight cutoff up to about 50,000 Daltons, remove theflavoring compounds as permeate, and remove the remaining whey proteinsand other whey materials as retentate.

(4) Neutralize the retentate and recover the whey proteins.

All types of whey protein materials are considered to be potentialsources of whey protein for use in the present invention and ultimatelyfor use in food products. Thus, for example, suitable whey proteinmaterials includes whey obtained from conventional cheese makingprocesses, whey protein isolate, whey protein concentrate, and the like.Thus, whey protein materials which contain whey proteins are provided inor combined into an aqueous mixture, generally a slurry of whey proteinsolids. The protein content is needed for food products, but asdiscussed above, it is believed to contain flavoring compounds whichmust be released in order that they can be separated. The separation offlavoring compounds is carried out in an aqueous mixture in which boththe proteins and flavoring compounds are dissolved. The concentration ofthe whey protein materials in the aqueous mixture will be in the rangeof about 1 to about 50 percent. Generally, the concentration of wheyprotein materials after pH adjustment will change during the subsequentultrafiltration step as water is removed with the permeate. The waterwill be replaced either periodically or continuously. For example, indiafiltration water is added to gradually dilute the retained proteinsin a batch or semi-continuous process.

The second step, as will be seen in the examples, is important ifremoval of the flavoring compounds is to be accomplished. The wheyproteins are solubilized by adding the appropriate pH-modifying agentbase to the aqueous mixture to achieve either a pH of about 8.5 to about12 (the basic mode of operation) or a pH of about 2.5 to about 4 (theacidic mode of operation).

For the basic mode of operation, it has been found that a pH of about8.5 or above is needed to maintain the solubility of the whey proteinsduring ultrafiltration, while a pH higher than about 12 is likely tocause undesirable degradation of the proteins. While in theory, any basemight be used, sodium or potassium hydroxide are preferred, particularlypotassium hydroxide. Other bases which may have application includecalcium, magnesium and ammonium hydroxides. For the acidic mode ofoperation, while in theory any edible acid might be used, phosphoricacid, citric acid, and malic acide are preferred, with phosphoric acidbeing particularly preferred.

It is believed that maintaining the solubility of solubilizing the wheyproteins during ultrafiltration allows the flavoring compounds to remainin a form in which they can be removed; if the whey protein denatureduring ultrafiltration, the flavoring compounds may become bound orencapsulated by the whey proteins, thereby preventing or reducing theeffectiveness of their removal. The flavoring compounds, which haverelatively low molecular weight compared to the whey proteins are ableto pass through the pores of the ultrafiltration membrane, whilesubstantially all of the solubilized whey proteins are too large and areretained. Importantly, the pH should be maintained within the justdescribed ranges (i.e., about 8.5 to about 12 for the basic mode ofoperation or about 2.5 to about 4 for the acidic mode of operation)during the ultrafiltration/diafiltration process to allow as much of theflavoring compounds as possible to be removed.

The third step could be carried out in a batch manner similar to thelaboratory experiments reported below in Examples 1-5 in which theflavor compounds and water passed through the membrane and were removedby flowing water. However, in commercial applications of the process ofthe invention, the pH-adjusted aqueous mixture would be circulatedcontinuously adjacent to an ultrafiltration membrane. Since water, thepH-modifying agent, and the flavoring compounds pass through themembrane as permeate and are discarded, additional water will be addedto maintain the desired concentration of whey protein materials, whichwill tend to change the pH of the aqueous mixture. This water may beaugmented by dewatering the permeate and recycling the recovered waterto the feed stream. A pH-modifying material (e.g., base or acid asappropriate) can be added as necessary to control the pH in the desiredrange (i.e., about 8.5 to about 12 for the basic mode of operation orabout 2.5 to about 4 for the acidic mode of operation) ) directly to theultrafiltration solution, to any recycled aqueous material, or to makeupwater as desired.

After removal of the flavoring compounds (i.e., after completion of theultrafiltration process), further neutralization of the filteredsolution may be accomplished by withdrawing product and adding an acidas required to reach the desired pH. After pH adjustment, the aqueousmixture of whey proteins and other materials may be used directly infood products, or it may be concentrated or dried as required for theintended use.

A process for deflavoring whey protein materials by ultrafiltration maybe operated in various ways. The pH during theultrafiltration/diafiltration process is maintained in the desired range(i.e., about 8.5 to about 12, and preferably about 9.5 to about 10.5,for the basic mode of operation; or about 2.5 to about 4, and preferablyabout 2.8 to about 3.8, for the acidic mode of operation). Two methodswill be described, continuous processing and batch (includingsemi-continuous operation) processing. It is expected that commercialprocesses will adopt batch or semi-continuous operation, which should bebetter suited to production of food-grade whey protein products. Acontinuous process is generally shown in FIG. 1. In either a continuousor batch process an aqueous mixture of whey protein materials is pHadjusted to solubilize whey proteins and release flavor compounds andthen passed adjacent an ultrafiltration membrane which permits the lowermolecular weight flavoring materials to pass through its pores alongwith water (the permeate), leaving the higher molecular weight wheyprotein materials (the retentate) to be recirculated. A portion of theretentate will be withdrawn as deflavored product, from which the wheyprotein materials can be recovered as needed for the ultimate end use.Water will be added to replace that lost in the permeate and to providea constant concentration of whey protein materials in the feed streamsupplied to the ultrafiltration membrane. Although not essential to theprocess, the process of FIG. 1 includes additional processing of thepermeate to recover a portion of the water using a reverse osmosismembrane for recycling to join the retentate and fresh whey proteinmaterials. The advantage of such a step is in reducing the amount offresh water which must be added to the process and removed inconcentrating the permeate. Of course, the pH of the whey proteinmaterials can be kept within the desired range by appropriate additionof a base or acid, as appropriate, to the recycled or fresh water addedto the process or by direct addition of base as desired.

In a batch process, such as those described in Examples 6-8 below, abatch of whey protein material is placed in a vessel, pH adjusted, andfed to an ultrafiltration membrane. The permeate is separated and theretentate is returned to the vessel. As the process proceeds, the wheyprotein material is depleted in the lower molecular weight flavoringcompounds and water and becomes more concentrated in the desirable wheyproteins. Periodically, water is added to the retentate to dilute it andprovide a carrier for the flavoring compounds which are passed throughthe membrane. In a semi-continuous process the water is addedcontinuously at the rate it is being removed in the permeate. Theprocess is continued until all of the flavoring compounds have beenremoved and the retentate is sufficiently deflavored to become theproduct, which can be further processed as required for the ultimate enduse. A batch or semi-continuous process may also include theconcentration of the permeate, with recycle of separated water in asimilar manner as that shown in FIG. 1. The pH during theultrafiltration/diafiltration process is maintained in the desired range(i.e., about 8.5 to about 12, and preferably about 9.5 to about 10.5,for the basic mode of operation; or about 2.5 to about 4, and preferablyabout 2.8 to about 3.8, for the acidic mode of operation).

The ultrafiltration membrane will be operated with a pressuredifferential across the membrane which assists migration of theflavoring compounds, water and other materials which are capable ofpassing through the pores of the membrane, while not exceeding thephysical strength of the membrane. Typical average pressure for suchmembranes are about 50 psi (345 kPa). The trans-membrane pressure (inversus out) will be about 15 psi (103 kPa). Of course, these pressurescould be varied based on the membrane's specifications and otheroperational concerns. The flow rate of the feed stream will providesufficient residence time for significant permeate removal, but alsowill be high enough to provide turbulence so that the access of the feedstream to the membrane pores will not be hindered by solid deposits onthe membrane walls. One skilled in the art will understand that suitableoperating parameters will be determined by experience with the materialsbeing separated.

In a preferred embodiment (i.e., the basic mode of operation), thepresent invention provides a method for preparing deflavored wheyprotein material, said method comprising: (a) providing an aqueouscomposition of a whey protein material containing soluble whey proteins,flavoring compounds, and insoluble materials; (b) solubilizing the wheyproteins by adjusting the aqueous composition of (a) to a pH in therange of about 8.5 to about 12 and releasing the flavoring compounds;(c) removing the insoluble materials from the pH-adjusted aqueouscomposition of (b) to obtain a treated aqueous composition; (d) passingthe treated aqueous composition of (c) adjacent an ultrafiltrationmembrane having a molecular weight cutoff up to about 50,000 Daltons,while maintaining the pH in the range of about 8.5 to about 12, undersuitable ultrafiltration conditions wherein the flavor compounds passthrough the membrane, thereby deflavoring the whey protein material andretaining substantially all of the solubilized whey proteins; and (e)recovering the solubilized whey proteins retained by the ultrafiltrationmembrane to obtain the deflavored whey protein material.

In another preferred embodiment (i.e., the acid mode of operation), thepresent invention provides a method for preparing deflavored wheyprotein material, said method comprising: (a) providing an aqueouscomposition of a whey protein material containing soluble whey proteins,flavoring compounds, and insoluble materials; (b) solubilizing the wheyproteins by adjusting the aqueous composition of (a) to a pH in therange of about 2.5 to about 4 and releasing the flavoring compounds; (c)removing the insoluble materials from the pH-adjusted aqueouscomposition of (b) to obtain a treated aqueous composition; (d) passingthe treated aqueous composition of (c) adjacent an ultrafiltrationmembrane having a molecular weight cutoff up to about 50,000 Daltons,while maintaining the pH in the range of about 2.5 to about 4, undersuitable ultrafiltration conditions wherein the flavor compounds passthrough the membrane, thereby deflavoring the whey protein material andretaining substantially all of the solubilized whey proteins; and (e)recovering the solubilized whey proteins retained by the ultrafiltrationmembrane to obtain the deflavored whey protein material.

These preferred embodiments are illustrated in FIG. 2 wherein the pH ofan aqueous solution of whey protein is adjusted to either (1) about 8.5to about 12 for the basic mode of operation or (2) about 2.5 to about 4for the acidic mode of operation. The pH-adjusted aqueous solution isthen treated to remove insoluble materials. Any conventional technique(e.g., filtration, decantation, centrifugation, and the like) can beused. Preferably, the insoluble material is removed by centrifugation.Commercial available continuous centrifugation units are ideally suitedfor this separation in a semi-batch or continuous type operation. In anespecially preferred embodiment, the pH-adjusted aqueous is subjected tothe removal technique (e.g., centrifugation) at least twice in orderfacilitate or more complete removal of insoluble materials. The treatedsupernatant is then subjected to ultrafiltration, preferably combinedwith diafiltration, in order to remove the flavor components normallyassociated with whey and whey protein compositions. Duringultrafiltration, the pH of the whey protein material should bemaintained in the same range as used in the initial adjustment of theaqueous solution. The deflavored whey protein solution may be useddirectly or it may be converted to a solid form if desired. Anyconventional technique for removing water can be used. Generally, sprayor freeze drying techniques are preferred.

Deflavored Whey Protein Products. The deflavored whey protein materialsprepared by the present methods are ideally suited for use in dairy andnon-dairy beverages, smoothies, health drinks, cheeses, cheese analogs,dairy and non-dairy yogurts, meat and meat analog products, cereals,baked products, snacks, and the like. Generally, such food products maycontain up to about 40 percent deflavored whey proteins withoutsignificantly impacting organoleptic properties. More preferably, suchfood products contain about 10 to about 30 percent deflavored wheyproteins. Using the deflavored whey protein of this invention it is nowpossible to incorporate whey protein in conventional food products atsufficiently high levels (generally sufficient to provide about 2.5 toabout 20 g whey protein per single serving size (generally about 25 toabout 100 g for solid food products and about 100 to about 300 ml forliquid food products)) to provide health benefits of whey protein. Priorto this invention, incorporation whey proteins at such levels generallyresulted in significant off-flavors and, therefore, only very limitedacceptance by consumers.

Unless noted otherwise, all percentages are by weight. All referencescited herein are incorporated by reference.

EXAMPLE 1

Whey protein concentrate (30 lbs. of WPC34 (34 percent protein; LeprinoCo., Denver, Colo.) was hydrated with water (170 lbs.) in a mixing tankwith vigorous mixing at a temperature of about 120° F. Once hydrationwas complete (generally within about 10 minutes), the pH was adjusted to9 using 1 N NaOH. The pH-adjusted solution was then diafiltered througha ultrafiltration membrane (spiral wound type with 10,000 molecularweight cut-off). Diafiltration was continued for an equivalent of 5 washcycles (each wash defined as the amount of permeate collected equal toone-half of the initial batch size). The pH was maintained at about 9during the ultrafiltration/diafiltration process. Once diafiltration wascompleted, solids in the retentate was concentrated to about 20 percentand citric acid (1%) was added to adjust the pH to 6.0. The resultingslurry was freeze dried to obtain a solid deflavored whey proteinmaterial. The deflavored whey protein material was found to containabout 2.8 percent ash, about 10.2 percent carbohydrates, about 8.4percent fat, about 2.2 percent moisture, and about 76.3 percent protein.

Slurries of the defavored whey protein material and several wheyprotein-containing control samples were prepared by hydrating the solidmaterials in water at about 100° F. for about 30 minutes. The samplesgenerally contained about 8 g whey protein per 100 g solution. Controlsincluded untreated WPC34 as well as untreated AMP 800 (80 percentprotein; Leprino Co., Denver, Colo.). The AMP 800 containedapproximately the same protein level as the deflavored whey proteininventive sample.

Based on an evaluation using a trained taste panel, the deflavored wheyprotein sample had the best overall taste, followed by the AMP 800control, with the WPC34 (untreated) having the most off flavors. Morespecifically, the lactose, milky, and animal flavors normally associatedwith whey proteins (and detected in both control samples) wereessentially eliminated in the inventive sample.

EXAMPLE 2

The deflavored whey protein sample prepared in Example 1 was used toprepare a high protein beverage. The following formulation was prepared:87.3 percent water, 7.0 percent deflavored whey protein, 2.5 percentsalt, 2.5 percent sugar, and 0.2 percent peach flavors. The drycomponents were first blended and the hydrated in the water using anoverhead mixer. Once hydration was complete, the flavor component wasadded. Stabilizers such as pectin and carrageenan could be added ifdesired to adjust final product viscosity to the desired level. Sugarcould be replaced to high corn syrup or other natural or artificialsweeteners if desired. Based on taste evaluation using a trained tastepanel, the beverage was considered excellent with regard to overallmouthfeel and flavor with no off-flavors detected. The resultingbeverage delivers about 13 g whey protein per 250 ml serving size.

EXAMPLE 3

This example illustrates the preparation of deflavored whey protein fromsweet whey. A clarified sweet whey (also known as rennet whey or cheesewhey) was obtained from a cheese making process. The sweet wheycontained about 12 percent protein, about 78 percent carbohydrates, andabout 1.1 percent fat on a dry basis (remainder mainly ash). The sweetwhey had been clarified using centrifugation to remove fat, cheesefines, and caseins, thereby significantly reducing fouling andincreasing flux rates in the subsequent ultrafiltration step. About 700pounds of the sweet whey was heated to about 120° F. in a jacketedreactor; the pH was then adjusted to about 7.5 with the addition of 1NNaOH. The alkalized whey was then continuously concentrated usingultrafiltration/diafiltration as in Example 1 using a UF sprial membranewith a 10000 molecular weight cutoff. Retentate was recirculated andmaintained at about 5 percent solids. Once the solids in the permeatereached about 50 percent of the original solids in the retentate, the pHwas readjusted to about 9 using 1N NaOH; the pH was maintained at aboutthe same level throughout the remainder of the UF/DA process.Diafiltration was continued at a constant solids level by the additionof reverse osmosis water at the same rate as removal of permeate untilthe ratio of solids in the permeate to solids in the retentate reachedabout 0.1 to about 0.15. The retentate was concentrated to about 10percent solids, collected, neutralized to pH 6.5 using citric acid (1percent), and then pasteurized (165° F. for 30 seconds). The pasteurizedproduct was then refrigerated before evaluation. The resulting productcontained about 68 percent protein, about 16 percent carbohydrates, andabout 6.3 percent fat on a dry basis. The flavor was bland with nooff-flavors making it ideal for incorporation into beverages and otherfood products.

EXAMPLE 4

This example illustrates the preparation of deflavored whey protein fromacid whey. Clarified acid whey as concentrated to about 14 percentsolids and about 50 percent protein. Clarification was by carried out bycentrifugation as in Example 3. Concentrated acid whey (200 pounds) wasdiluted with about 200 pounds reverse osmosis water and then heated toabout 120° F. in a jacketed tank. The pH of the slurry (initially about4.7) was adjusted to about 9 by slowly adding 1 N NaOH. The alkalizedwhey was then continuously concentrated usingultrafiltration/diafiltration as in Example 1 using a UF sprial membranewith a 10000 molecular weight cutoff. Reverse osmosis water was added asneeded to maintain solids at about 4 to about 7 percent. The pH wasmaintained at about 9 throughout the UF/DA process. Diafiltration wascontinued at a constant solids level by the addition of reverse osmosiswater at the same rate as removal of permeate until the ratio of solidsin the permeate to solids in the retentate reached about 0.1 to about0.15. The retentate was concentrated to about 14 percent solids,collected, neutralized to pH 6.5 using citric acid (1 percent), and thenpasteurized (165° F. for 30 seconds). The pasteurized product was thenrefrigerated before evaluation. The resulting product contained about 80percent protein, about 9 percent carbohydrates, and about 4 percent faton a dry basis (remainder mainly ash). The flavor was bland with nooff-flavors making it ideal for incorporation into beverages and otherfood products. A portion of the product was spray dried for further useand evaluation.

EXAMPLE 5

This examples illustrates the preparation of a high-acid fruit juicebeverage containing about 8 g protein per single serving size (about 240ml) derived from the spray dried deflavored acid whey of Example 4. Thebeverage was prepared using the following formulation: Ingredient Amount(%) Water 79.3 Deflavored Acid Whey Powder 4.1 Evaporated Cane Juice 9.0Alginate 0.3 Citric Acid 0.1 Malic Acid 0.2 Phosphoric Acid (80%) 0.1Ascorbic Acid 0.03 Strawberry Juice Concentrate (65 Prix) 0.4 WhiteGrape Juice Concentrate (68 Prix) 6.4 Strawberry Flavor 0.2 Coloring(red) 0.002The deflavored acid whey powder was hydrated in a portion of the water(at about 160° F.). The remainder of the water was to about 160° F. andthe alginate and evaporated cane juice added with high agitation. Thehydrated whey powder mixture was then added, followed by the variousacids, juice concentrates, and remaining ingredients. The mixture washomogenized using a high speed mixer for about 5 minutes. The resultingmixture, which had good flavor, had a pH of about 4.1. Lower pH values(e.g., about 3.5 to about 4) increases stability. Likewise, stabilizers(e.g., pectin, poly-glutamic acid, and the like) can be added atrelatively low values (e.g., about 0.3 to about 0.4 percent) to increasestability if desired.

EXAMPLE 6

This examples illustrates the preparation of a low acid chocolatebeverage containing about 8 g protein per single serving size (about 240ml) derived from the deflavored acid whey of Example 4. The beverage wasprepared using the following formulation: Ingredient Amount (%) FilteredWater 83.4 Deflavored Acid Whey Powder 4.1 Potassium Citrate 0.4 SeaSalt 0.03 Microcrystalline Cellulose 0.25 Evaporated Cane Juice 8.5Cocoa 1.5 Cream 1.5 Vanilla Flavor 0.3The filtered water was divided into two portions of about the same size.The deflavored acid whey powder, about 60 percent of the evaporated canejuice, the microcrystalline cellulose, potassium citrate, and the seasalt were preblended and then added to the first water portion with highagitation to form a first slurry; the cream was then added to the firstslurry. The cocoa and the remainder of the evaporated can juice werethen preblended and then added to the second water portion with highagitation to form a second slurry. The second slurry was then mixed withthe first slurry and then homogenized in a two stage homogenizer(2500/500 psi). After pasteurization at about 195° F. for about 5 toabout 10 seconds, the beverage was sealed in heat stable containers andthen chilled to about 45° F. Evaluation with a trained test panelindicated that the product had good mouthfeel and texture, excellentcocoa aroma, and pleasant chocolate flavor with no off-flavors orundesirable aftertaste. The vanilla flavor was apparently at too low aconcentration to be detected; it may be desirable to increase its level.

EXAMPLE 7

This example illustrates the acidic mode of operation for thedeflavoring process. Clarified concentrated acid whey (300L lbs; WPC 50as used in Example 4; initial pH 4.7) was diluted with 100 lbs ofdeionized water in a jacketed tank with overhead mixing. The mixture washeated to about 120° F. by circulating hot water through the jacket. ThepH was then adjusted to 3.2 by slowly adding 10% phosphoric acid. ThepH-adjusted whey solution was allowed to equilibrate for about 10minutes and then was continuously concentrated usingultrafiltration/diafiltration as in Example 1 using a UF sprial membranewith a 10000 molecular weight cutoff. Continuousultrafiltration/diafiltration was carried out for an equivalent of 6wash cycles at which time the amount of solids in permeate was close tozero. The pH was maintained at about 3.2 throughout the UF/DA process.The retentate was then concentrated to a solids content of about 12percent. The product was then batched pasteurized at 165° F. for 5minutes. The pasteurized product was then refrigerated beforeevaluation. The resulting product contained about 80 percent protein,about 5 to about 10 percent carbohydrates, and about 1 to about 3percent fat on a dry basis (remainder mainly ash). The flavor was blandwith no off-flavors making it ideal for incorporation into beverages andother food products.

EXAMPLE 8

This example illustrates the preparation of a mixed berry, high acid,whey-containing beverage using the deflavored whey protein obtained inExample 7. The following formulation was used: Ingredient Amount (%)Deionized Water 38.8 Deflavored Acid Whey (liquid) 45.6 Sucrose 11.1Strawberry Juice Conc. (65 Brix) 0.7 White Grape Juice Conc. (68 Brix)1.8 Clarified Orange Juice Conc. (58 Brix) 1.0 Sour Cheery Juice Conc.(68 Brix) 0.2 Red Raspberry Juice Conc. (68 Brix) 0.2 Coloring 0.001Sodium Citrate 0.05 Natural Cherry Flavor 0.05 Natural Mixed BerryFlavor 0.3 Natural Blueberry Flavor 0.04 Vitamin Mixture 0.02 OtherNatural Flavors 0.1The deionized water at 150° F. and the deflavored whey were mixedtogether. The remaining ingredients were then added in the followingorder with blending: dry ingredients (sucrose, sodium citrate, vitaminpremix, coloring), juice concentrates, and flavors. The resultingbeverage was filled into sterile 1-liter bottles. The product waspreheated to 170° F. in preheat exchangers and then pasteurized at aminimum temperature of 230° F. and a minimum time of 2 seconds. Theproduct was homogenized at 170° F., then cooled to about 40° F., andfilled into individual bottles.

A beverage prepared in such a manner would be expected to have thefollowing nutritional characteristics per single serving size of about258 g; Calories: 150; Total Fat: 0 g; Cholesterol: 0 mg; Sodium: 30 mg:Total Carbohydrate: 26 g; Dietary Fiber: 0 g; Sugars: 24 g; Protein 10g; Vitamin A: 30%; Vitamin C: 30%; Calcium 15%; Vitamin E: 30%. Such abeverage would be considered fat free, saturated fat free, andcholesterol free as well as being an excellent source of protein andvitamins A, C, and E.

The finished product provided excellent mouthfeel and was lessastringent than similar products prepared with non-deflavored wheyproducts. Since the deflavored whey material was prepared using the acidmode of operation, its pH was close to the desired pH of the finalbeverage and, therefore, it was not required to be adjusted in such amanner as to pass through its isoelectric point.

1-23. (canceled)
 24. A whey-containing food product comprising a deflavored whey protein material, wherein the whey-containing food product is prepared by incorporating the deflavored whey protein into a food product and wherein the deflavored whey protein is prepared by a process comprising: (a) preparing an aqueous composition comprising a dairy-derived whey protein material containing soluble whey proteins and flavoring compounds; (b) adjusting the aqueous composition of (a) to either (1) a basic pH in the range of about 8.5 to about 12 using addition of alkali to the aqueous composition, or (2) an acidic pH in the range of about 2.5 to about 4 using addition of acid to the aqueous composition, thereby releasing the flavoring compounds; (c) passing the pH-adjusted aqueous composition of (b) adjacent an ultrafiltration membrane having a molecular weight cutoff up to about 50,000 Daltons, while maintaining the pH in the same range as adjusted in step (b), under suitable ultrafiltration conditions wherein the flavor compounds pass through the membrane, thereby deflavoring the whey protein material and retaining substantially all of the soluble whey proteins; and (d) recovering the soluble whey proteins retained by the ultrafiltration membrane to obtain the deflavored whey protein material.
 25. The whey-containing food product of claim 24, wherein the pH of the aqueous composition is adjusted to the basic pH in step (b).
 26. The whey-containing food product of claim 24, wherein the pH of the aqueous composition is adjusted to the acidic pH in step (b).
 27. The whey-containing food product of claim 24, wherein the food product is selected from the group consisting of dairy and non-dairy beverages, smoothies, health drinks, cheeses, cheese analogs, dairy and non-dairy yogurts, meat and meat analog products, cereals, baked products, and snacks.
 28. The whey-containing food product of claim 24, wherein the whey-containing food product contains about 10 to about 30 percent deflavored whey protein.
 29. The whey-containing food product of claim 25, wherein the whey-containing food product contains about 10 to about 30 percent deflavored whey protein.
 30. The whey-containing food product of claim 26, wherein the whey-containing food product contains about 10 to about 30 percent deflavored whey protein.
 31. The whey-containing food product of claim 25, wherein the whey-containing food product is a beverage having a pH of greater than
 5. 32. The whey-containing food product of claim 26, wherein the whey-containing food product is a beverage having a pH of less than 4.5. 